Electrical machine, especially electric motor

ABSTRACT

A brush mounting plate for an electric motor is formed as a one piece element molded from a suitable electrically non conductive material. The plate is formed with various openings, recesses and lugs on its opposed faces which serve to mount and locate components such as brush holders, inductors, and thermo switches in a compact arrangement with various components assembled to opposite faces of the plate in a stacked relationship axially of the plate. The lugs are so arranged as to enable a snap fit assembly of the inductor and thermo switches on to the plate.

BACKGROUND OF THE INVENTION

The present invention is directed to a brush mounting assembly for anelectric motor.

It is known in the prior art to mount the brushes of an electric motorupon a plate or frame which is also employed to mount other electriccomponents, such as the inductors, etc. of a noise suppression circuitand thermal switches for interrupting the motor circuit in the event ofover heating. These mounting plates are customarily formed with acentrally located opening through which the motor armature projects,with the brush holders located at dynamically opposite sides of thecentral opening. Space is at a premium, and the locating and mounting ofthe brushes and associated circuit elements upon the relatively smallmounting plate in a compact manner such that the individual elements maybe easily assembled and accessibly presents problems which have not beenfully solved in the prior art.

SUMMARY OF THE INVENTION

In accordance with the present invention, a disk-like brush mountingplate is formed of a suitable non-electrically conductive plasticmaterial as an integral one-piece molded structure. The mounting plateis provided with openings through which tabs of metal brush holders maybe projected and bent into place, and with recesses and projecting lugsassociated with the various recesses arranged in a manner such thatcircuit components, such as inductors or thermal switches may readily beassembled on to the plate by a snap fit. The plate is so designed thatcertain components, when assembled to the structure, are located on oneside of the disk like plate, while other components are located on theopposite side of the plate--i.e. the components are axially spaced fromeach other in relationship to the axis of the central armature receivingopening to achieve a very compact assembly.

Other objects and features of the invention will become apparent byreference to the following specification and to the drawings.

IN THE DRAWINGS

FIG. 1 is an end view of the rear face of a brush mounting structureembodying the present invention;

FIG. 2 is a cross-sectional view of the structure of FIG. 1 taken on theline II--II of FIG. 1;

FIG. 3 is an end view of the front face of the mounting structure ofFIG. 1;

FIG. 4 is an rear view of the mounting structure of FIG. 1 showingvarious circuit components assembled to the mounting structure;

FIG. 5 is a cross-sectional view taken on the line V--V of FIG. 4;

FIG. 6 is a partial view of a housing cover employed with the mountingstructure; and

FIG. 7 is a detailed cross-sectional view showing the manner in which atubular rivet is mounted upon the mounting structure of the precedingfigures.

A brush assembly embodying the present invention includes a one-piecemounting plate designated generally 10 of a suitable non conductiveplastic material preferably formed by a molding operation. Mountingplate 10 includes a planar disk-like main portion 11 formed on its front25 and rear 19 faces with various apertures and projecting lugs to bedescribed below. In FIGS. 1-3, mounting plate 10 is shown alone, whilein FIGS. 4 and 5, which correspond to FIGS. 1 and 2, mounting plate 10is shown with various electrical and mechanical components assembled toit.

Mounting plate 10 is formed with a centrally located opening 9 throughwhich, when the plate is assembled with an electric motor in awell-known manner, the motor armature will project. A pair of hollow,tubular brush holders 12 (FIGS. 4 and 5) which slidably receive motorbrushes 13 may be mounted upon the rear side of the disk-like mainportion 11 by means of mounting tabs 12a formed on brush holder 12 whichproject through slot-like openings 14 (FIGS. 1 and 3) through mainportion 12 to be bent into engagement with the front face 25 to retainbrush holder 12 in position. Preferably, the rear face 19 of mainportion 11 is formed with projecting ribs 12b which extend along andengage opposed sides of the tubular brush holders 12 as best seen inFIGS. 4 and 5 to locate the elongate brush holders 12 in radialalignment with the axis of opening 9. Radial outward movement of brushholders 12 is limited by lugs 15 (FIG. 4) which engage the outer ends ofholders 12.

A pair of elongate recesses 16 which open through main portion 11 arelocated at diametrically opposed sides of opening 9 to extendlongitudinally in parallel relationship to the longitudinal orientationof brush holders 12 established by ribs 12b. Referring now particularlyto FIGS. 1 and 2, tab like projections 17 formed on mounting plate 12project into recess 16 from opposite sides and are formed with concaveforwardly (upwardly as viewed in FIG. 2) facing surfaces. Lugs 26, 27(FIGS. 2 and 4) projecting from the front face 25 of mounting plate aredisposed upon opposite sides of the respective recesses 16 and, as bestseen in FIG. 2, are formed with concave recesses which, when viewedlongitudinally of recesses 16 as in FIG. 2, form a smooth continuationof the concave surfaces of projections 17. Ratchet lug sections as at 28are disposed on members 26 (FIG. 2) so that the concave surfaces onprojections 17 and lugs 26, 27 form a generally cylindrical recess asviewed in FIG. 2 into which a cylindrical inductor coil 31 (FIGS. 4 and5) can be snap fitted by pressing the coil downwardly into the recess inthe front face until the coil snaps beneath the ratchet sections 28.Projections 29 (FIG. 3) on the front face 25 limit axial movement of thecoil 31, once it is in position.

A series of lugs 37, 38, 39 and 40 projecting from the rearward face 19of main portion 11 of the mounting plate cooperatively define recesses35 which are conformed to receive a rectangular box-like (cuboid) thermoswitch 36 (FIGS. 4 and 5). As best seen in FIG. 2, lugs 37 projectrearwardly from rear face 19 and are formed at their rearward ends withan inwardly projecting toe portion 37a. Lugs 38 project rearwardly fromface 19 in facing opposed space relationship to lugs 37. Lugs 39 and 40also project rearwardly from surface 19. Lug 39 is a relatively shortlug which acts as a locking detent.

Referring now to FIG. 5 the thermo switch 36 is inserted into itsassembled position by inclining it upwardly (as viewed in FIG. 5),upwardly through the opening between the lower end of lug 38 and theprojecting tow 37a. The lug 38 and toe portion 37a possess sufficientresilience so that switch 30 can be forced into the position shown inFIGS. 4 and 5 where the opposed sides of the switch 36 as viewed in FIG.3 are engaged between the facing surfaces of lug 38 and lug 37. Asviewed in FIG. 5, the top surface of switch 36 is engaged beneath theprojections 17 which define the bottom of recess 16 and support theinductor 31, while the lower surface of switch 36 as viewed in FIG. 5 isseated upon toe portion 37a of lug 37. Referring now to FIG. 4, it isseen that the remaining opposed end surfaces of switch 36 are engaged atone end by a lug 40 and at the opposite end by the detent like lug 39.Lug 40 likewise possesses sufficient resilience so that switch 36 may betilted as may be convenient in inserting or replacing the switch, therelatively short detent like projection 39 providing a detent like lockholding the switch in its final assembled position.

It is believed apparent from the foregoing that the inductors 31 aresnapped fitted into assembled positions upon the mounting plate from thefront side of the plate and that these assembled positions areestablished by the various recesses, projections and lugs describedabove. Similarly, the thermo switch is assembled to mounting plate 10from its rear side, and again is snap fitted into a position establishedby the various lugs integrally formed on the mounting plate as describedabove.

As best seen in FIG. 5, this arrangement enables a thermo switch 36 andinductor 31 to be stacked axially of the assembly relative to oneanother so that an extremely compact assembly is achieved. Although FIG.5 shows only one thermo switch 36, it is believed apparent that ifdesired, a second thermo switch 36 could be assembled into theunoccupied space 35 at the opposite side of the mounting plate.

The various electrical components and the brushes 13 are electricallyconnected with each other and, via supply cables 43 and 44, to anexternal voltage source (not shown). To guide the various electricalleads or cables across the front face of mounting plate 10, forwardlyprojecting posts 45 (FIGS. 3, 5) are formed on mounting plate 10, onepost 45 being located in adjacent spaced relationship to each lug 26 toform a guide channel, as for the cable 44 as seen in FIG. 5. At therearward face 19, where more space is available, leads such as 42 whichconnect a terminal 41 on the thermol switch to a carbon brush are keptrelatively short and need no guidance.

Mounting plate 10 is further formed with bores 51 (FIGS. 3 and 7) whichprovide a means for mounting tubular rivets 50 (FIG. 7). As best seen inFIG. 7, the bores 51 are formed within an enlarged diameter counter boreextending inwardly from front face 25. The tubular rivets 50 aresupplied with an outwardly projecting annular bead 52 which, as seen inFIG. 7, will seat against rear face 19 and the rivet is fixed to plate11 by radially extending the rivet walls into the large diameter counterbore potion of bore 51. This arrangement results in the projectingportion of the rivet 50 being located to project from the rear face 19of the mounting plate where more space is available. The supply leadsare inserted into rivet 50 from front fact 25 and, after the supply leadis properly positioned, the walls of rivet 50 are crimped tomechanically clamp the supply lead in place.

When assembled into an electric motor (not shown) an end cap 60 (FIG. 5)is fixedly attached to mounting plate 10 to overlie the front face 25 ofthe plate as shown in FIG. 5. Mounting plate 10 in turn is insertedaxially into the end of a hollow cylindrical cover 61 (FIG. 6), thescale of the cover as shown in FIG. 1 being smaller than that of theother figures. Cover 61 is formed at its end with recesses 62 which areconformed to receive lugs 63 (FIG. 4) which project rearwardly from rearface 19 and are of a configuration complementary to recesses 42 to aligncover 61 with mounting plate 10.

What is claimed is:
 1. A brush mounting device for mounting the elongatebrush holders, at least one first generally cylindrical circuitcomponent and at least one generally cuboid second circuit component ofan electric motor, said device comprising a one piece member of anelectrically non conductive material including a generally flat disclike plate portion having a front face, a rear face and a centralopening extending through said plate portion along an axis perpendicularto said front and rear faces, first means on said plate portion forfixedly mounting a pair of elongate brush holders upon said rear face atdiametrically opposite sides of said central opening with thelongitudinal axes of said holders in alignment with each other, saidmeans integral with said plate portion for mounting a pair of firstgenerally cylindrical circuit components upon the front face of saidplate portion at diametrically opposite sides of said central openingwith the longitudinal axes of said first components extending parallelto each other, and third means integral with said plate portion formounting said at least one generally second circuit cuboid component onsaid plate portion upon the rear face of said plate portion directlyopposite one of said first generally cylindrical circuit components. 2.The invention defined in claim 1 wherein said second means comprisesmeans defining an elongate transversely concave seat in said front faceconformed to receive and locate said first generally cylindrical circuitcomponents upon said plate portion, a plurality of first lugs integralwith said plate portion projecting forwardly from said front face atopposite sides of said recess, and detent-like projections on the sidesof said lugs facing said recess for releasably retaining said firstgenerally cylindrical circuit components on said seat.
 3. The inventiondefined in claim 1 wherein said third means comprises a plurality ofsecond lugs integral with said plate portion and projecting downwardlyfrom said rear face, a first two of said second lugs being located inspaced opposed relationship to each other, one of the two last mentionedlugs having a toe portion at its rearward end projecting generallytoward the other of said two last mentioned lugs in spaced parallelrelationship to said rear face, said first two lugs being located on twoopposed sides of a rectangle conformed to one side of said cuboid secondcircuit component, a second two of said second lugs being located on thetwo remaining sides of said rectangle, one of the last mentioned twolugs projecting a relatively short distance from said rear face toconstitute a detent operable to releasably retain a second componentbetween said second lugs with a first two opposed sides of the at leastone generally second cuboid circuit component engaged between said firsttwo second lugs, a second two opposed sides of said second circuitcomponent engaged between said second two of said second lugs, and theremaining two opposed sides of said second component being engagedbetween said toe portion and said rear face.